Fast charge apparatus for a battery

ABSTRACT

A fast charge system 20 including a fast charge composite 60 and a secondary battery 22 enables the secondary battery 22 to be charged in less time than is possible with traditional charging means. The fast charge composite 60 includes a separator 62 of cellulose wetted with a second electrolyte 64 that contains third ions 94 having a positive charge and fourth ions 96 having a negative charge and contacting the adjacent electrode 32, 46 of the secondary battery 22. A fast charge layer 30 of thermally expanded graphite is disposed adjacent and parallel to the separator 62. A second electrical power PFC, which may be greater than a maximum charging power PMAX transferred through traditional charging, is transferred as a function of a second voltage V2 applied between the fast charge layer 30 and the battery lead 34, 50 of the adjacent electrode 32, 46, which causes the third ions 94 and the fourth ions 96 to migrate through the separator 62 to cause the secondary battery 22 to become charged.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of continuation-in-partU.S. patent application Ser. No. 14/607,530, filed Jan. 28, 2015 whichclaims the benefit of U.S. patent application Ser. No. 14/539,448 filedNov. 12, 2014, which claims the benefit of provisional application No.61/903,145 filed Nov. 12, 2013.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to a fast charge composite combined with asecondary battery for charging the secondary battery.

2. Description of the Prior Art

It is generally known to construct batteries as a stack of layers, witha cathode sandwiched with the membrane and disposed in spaced andparallel relationship with the anode and an electrolyte impregnating themembrane to carry an ion migration through the membrane. An example ofsuch a battery is shown in U.S. Patent Application 2009/0142668.

It is also known to construct a battery as a stack of layers that form aplurality of electrochemical cells which are connected in parallel or inseries. An example of such a battery construction is shown in U.S.Patent Application No. 2012/0058380.

Secondary battery cells that use an electrolyte to convey first ionshaving a positive charge and second ions having a negative chargebetween anode and cathode electrodes are well known. An example of sucha battery is shown in U.S. Pat. No. 4,707,423.

Secondary battery cells are typically charged using a traditionalcharging means of applying a first voltage between the anode and thecathode to cause a first current to flow therebetween. An example ofsuch charging is described in U.S. Pat. No. 7,489,107.

It is also well know that a secondary battery may only be recharged witha maximum charging power that is a function of the first voltage betweenthe anode and the cathode times the first current therebetween andapplied over a first time interval. There are two main types of damageto battery cells that result from application of power greater than themaximum charging power and cause a substantial loss in capacity. Thefirst main type of damage results from overheating, which causes damagethe battery cell through melting and/or the production of gasses (e.g.through boiling the electrolyte). Eventually, overheating damage cancause a short circuit between the electrodes. The second main type ofdamage is plating, also known as deposition, which occurs withintercalation electrodes that accept ions within a crystalline latticestructure. During normal operation, ions are chemically inserted intothe intercalation electrode, where they react with the electrode,trapping the metallic products of the reaction inside of the latticestructure. However, when a power greater than the maximum charging poweris applied, ions will react on the surface of an intercalation electrodeand cause a metallic layer to form or to be plated on that surface. Theformation of that metallic layer is uneven and can create needle-likedendrite structures that extend into the membrane, which can eventuallyshort-circuit the battery cell.

U.S. Pat. No. 6,117,585 to Anani et al. discloses a hybrid energystorage device constructed as a stack of layers, with two electrodelayers and a first electrolyte forming a battery. A second electrolyte,sandwiched between a third electrode and one of the battery electrodes,forms an electrolytic capacitor. The Anani et al. '585 device requiresan external conductor to directly connect the non-adjacent batteryelectrode to the capacitor electrode.

SUMMARY OF THE INVENTION

The invention provides for a fast charge composite with a secondelectrolyte that includes third ions having a positive charge and fourthions having a negative charge. The fast charge composite is disposedadjacent to and contacting one of the electrodes of a secondary battery,which is the adjacent electrode, and the remaining electrode of thesecondary battery is the remote electrode, which is electricallyisolated from the fast charge composite. The fast charge composite isresponsive to application of a second electrical power, which is greaterthan the maximum charging power that can be applied to the secondarybattery using the traditional charging means of applying a first voltagebetween the electrodes of the secondary battery to induce a firstcurrent therebetween. The second electrical power is a function of asecond voltage between the fast charge composite and the adjacentelectrode multiplied by the second current therebetween and applied overa second time interval. The application of the second electrical powercauses the third ions and the fourth ions to migrate between theadjacent electrode and the fast charge composite to change theelectrochemical potential of the adjacent electrode, which enables thesecondary battery to store the predetermined amount of electrical energyin a second time interval that is shorter than the first time intervalthat it would take using the traditional charging means at or below themaximum charging power. In other words, the battery can be charged toits capacity in a shorter time using the fast charge composite than ispossible using traditional charging means.

The invention also provides for a method of constructing such a fastcharge composite with a second electrolyte, including: dissolving AlCl₃in ethanol to create a background solution, combining the backgroundsolution with glycerol to make a second electrolyte including third ionshaving a positive charge and fourth ions having a negative charge, andwetting a separator of electrically insulating material with the secondelectrolyte.

Advantages of the Invention

The invention in its broadest aspect provides a fast charge compositethat allows a secondary battery to store a predetermined amount ofelectrical energy in less time than is possible using the traditionalcharging means of applying a first voltage and a first current betweenthe battery leads.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated,as the same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is a schematic cut-away view of a secondary battery with a fastcharge composite disposed adjacent a cathode layer of a secondarybattery.

FIG. 2 is a schematic cut-away view of a secondary battery with a fastcharge composite disposed adjacent an anode layer of a secondarybattery.

FIG. 3 is a cut-away top view of a secondary battery with a fast chargecomposite disposed below and adjacent a cathode layer of a secondarybattery.

FIG. 4 is a schematic of secondary battery being charged throughtraditional means and showing the movement of ions and conventional(positive) current flow.

FIG. 5 is a schematic of a fast charge system with a fast chargecomposite disposed adjacent a cathode layer and showing the movement ofions and conventional (positive) current flow while charging thesecondary battery using the fast charge composite and while dischargingthe secondary battery.

DESCRIPTION OF THE ENABLING EMBODIMENT

Referring to the Figures, wherein like numerals indicate correspondingparts throughout the several views, a fast charge system 20 including asecondary battery 22 with a capacity to store a predetermined amount ofelectrical energy is disclosed. The term “secondary battery” refers toan electrochemical energy storage device that is capable of beingrecharged.

As shown in the figures, the secondary battery 22 includes a pair ofelectrodes 32, 46 including an anode layer 32 and a cathode layer 46extending in parallel and spaced relationship to one another.

The anode layer 32 consists of 99.4 to 99.9 wt % of solid Aluminum of99.95% purity and 0.1 to 0.6 wt % of Indium with first rectangularborders to define a first length of 1.2 cm, a first width of 1.7 cm, anda first thickness of 0.1 mm. A negative battery lead 34 of electricallyconductive material is in electrical contact with the anode layer 32 forconducting electrical current with external circuitry for charging ordischarging the secondary battery 22. The negative battery lead 34 couldalso serve as a point of connection to another battery cell as part of amulti-cell battery device. The negative battery lead 34 could be a wire,pad, terminal, or any other suitable means of making an electricalconnection.

The anode layer 32 is attached in electrical contact with the negativebattery lead 34 using an electrically conductive cement 36 that includesparticles containing metal. Examples of such cements 36 are Two PartConductive Silver Paint (Part No. 12642-14), sold by Electron MicroscopySciences and Solder-It Aluminum Solder Paste, sold by SOLDER-IT, INC. ofPleasantville, N.Y.

The cathode layer 46 has a second rectangular border with a secondlength of 1.4 cm, a second width of 1.9 cm, and a second thickness of0.1 mm. The cathode layer 46 includes a carrier sheet 48 of celluloseand an electroactive layer 28 integrated within and disposed upon thecarrier sheet 48 on the side facing the anode layer 32. In other words,the electroactive layer 28 coats the surface and extends into thestructure of the carrier sheet 48. The electroactive layer 28 of thecathode layer 46 contains a host lattice 54 that defines a plurality ofvoids and includes a conjugated system with delocalized π electrons. Aconjugated system is defined as a system of connected p-orbitalscontaining delocalized electrons in chemical compounds. Morespecifically, the conjugation is the overlapping of one p-orbital withanother across adjacent single (sigma) bonds. One such compound that hassuch a conjugated system is graphite. Other compounds such as, but notlimited to, polyaniline and polyconjugated linear hydrocarbon polymersalso include conjugated systems with overlapping p-orbitals.

A positive battery lead 50 containing thermally expanded graphite iselectrically connected to the electroactive layer 28 of the cathodelayer 46 for conducting electrical current with external circuitry forcharging and/or discharging the secondary battery 22. An adhesive 52containing graphite attaches the electroactive layer 28 to the positivebattery lead 50 and conducts electrical current therebetween. One suchpositive battery lead 50 comprises thermally expanded graphite foil 66.An alternative positive battery lead 50 comprises a rod of graphite witha diameter of 0.1 mm. The positive battery lead 50 could also serve as apoint of connection to another battery cell as part of a multi-cellbattery device. The positive battery lead 50 could include a wire, pad,terminal, or any other suitable means of making an electricalconnection. However, conductors of metal should not be placed in directcontact with the host lattice 54 of the cathode layer 46 because themetal can migrate into the host lattice 54 and interfere with thefunctionality of the cathode layer 46 in charging and discharging thesecondary battery 22.

A dopant 58 containing Aluminum Alcoholate and Aluminum Glycerate isbonded to the conjugated system of the host lattice 54 to alter theelectrochemical properties of the electroactive layer 28 of the cathodelayer 46 to increase the rate of the reactions with the first ions 24and the second ions 26 for charging and discharging the secondarybattery 22. The dopant 58 is also intercalated in the host lattice 54 sothat particles of the dopant 58 are embedded in the voids of the hostlattice 54.

A membrane 38 of cellulose having a third thickness of 0.08 mm anddefining a plurality of pores is sandwiched between the anode layer 32and the cathode layer 46 for providing electrical insulation anddefining a first voltage V₁ therebetween. The membrane 38 is anelectrical insulator, but is permeable to dissolved ions.

The membrane 38 is wetted with a first electrolyte 44 so the firstelectrolyte 44 impregnates the pores of the membrane 38. The firstelectrolyte 44 includes first ions 24 that contain Aluminum and have apositive charge. The first electrolyte 44 also includes second ions 26that contain Aluminum and have a negative charge. The first electrolyte44 is damaged by application of a first voltage V₁ greater than apredetermined maximum voltage V_(MAX).

An excess ion migration is carried by the first electrolyte 44 throughthe membrane 38 in response to the application of a first current I₁between the positive battery lead 50 and the negative battery lead 34that is greater than a predetermined maximum current I_(MAX).

A maximum charging power P_(MAX) is defined as the first voltage V₁times the first current I₁, with either the first voltage V₁ beinggreater than the predetermined maximum voltage V_(MAX) or the firstcurrent I₁ being greater than the predetermined maximum current I_(MAX).

A secondary battery may be charged with a power less than the maximumcharging power P_(MAX) and applied over a first time interval T₁ as isthe case with the traditional means of charging a secondary battery 22,shown schematically in FIG. 4. Application of power in excess of themaximum charging power P_(MAX), between the between the positive batterylead 50 and the negative battery lead 34 can cause irreversible damageto the first electrolyte 44 and/or the membrane 38 and/or either of theelectrodes 32, 46, which substantially reduces the capacity of thesecondary battery 22.

The first electrolyte 44 consists essentially of glycerol and first ions24 containing Aluminum and having a positive charge, and second ions 26containing Aluminum and having a negative charge. The first ions 24include [Al(ClO₄)₂·{C₃H₅(OH)₃}₂]⁺, and the second ions 26 include[Al(ClO₄)₄]⁻. The first ions 24 and the second ions 26 migrate betweenand react with the anode layer 32 and the cathode layer 46 to charge anddischarge the secondary battery 22.

A fast charge composite 60 overlies and contacts one of the electrodes32, 46 of the secondary battery 22. The fast charge composite 60 has athird rectangular border with a third length and a third width that arebetween those of the first rectangular border of the anode layer 32 andthe second rectangular border of the cathode layer 46.

The fast charge composite 60 includes a separator 62 of cellulose thatis impregnated with a second electrolyte 64 that includes third ions 94containing Aluminum and having a positive charge. The second electrolyte64 also includes fourth ions 96 containing Aluminum and having anegative charge. The separator 62 is disposed parallel to and contactingone of the electrodes 32, 46, which is designated as the adjacentelectrode 32, 46. The other one of the electrodes 32, 46 that is not incontact with the separator 62 is designated as the remote electrode 32,46 and is electrically isolated from the fast charge layer 30. Theseparator 62 is an electrical insulator, but is permeable to dissolvedions.

The fast charge composite 60 also includes a fast charge layer 30comprising foil 66 of thermally expanded graphite which is disposedadjacent and parallel to the separator 62 so that the separator 62 issandwiched between the adjacent electrode 32, 46 and the fast chargelayer 30. A fast charge lead 68 of electrically conductive material iselectrically connected to the fast charge layer 30 for the applicationof second electrical power P_(FC), which is greater than the maximumcharging power P_(MAX) which can be applied between the battery leads34, 50.

The second electrical power P_(FC) is a function of a second voltage V₂between the fast charge lead 68 and the battery lead 34, 50 of theadjacent electrode 32, 46 times a second current I₂ that flows throughan external circuit between the fast charge lead 68 and the battery lead34, 50 of the adjacent electrode 32, 46 and applied over a second timeinterval T₂.

The second electrical power P_(FC) causes the third ions 94 and thefourth ions 96 to migrate through the separator 62 between the adjacentelectrode 32, 46 and the fast charge layer 30 to change theelectrochemical potential of the adjacent electrode 32, 46 and to causethe secondary battery 22 to store the predetermined amount of electricalenergy in a shorter second time interval T₂ than the first time intervalT₁ when subjected at or below the maximum charging power P_(MAX) bytraditional charging means. In other words, it is possible to charge thesecondary battery 22 using the fast charge composite 60 in less timethan is possible through traditional charging by applying a firstvoltage V₁ and a first current I₁ between the battery leads 34, 50. FIG.5 is a schematic representation of the application of the secondelectrical power P_(FC) to the fast charge layer 30 by application ofthe second voltage V₂ and the second current I₂. FIG. 5 also shows thesecondary battery 22 transferring power into a resistive load connectedbetween the battery leads 34, 50 at the same time as the secondarybattery 22 is being charged using the fast charge composite 60.

The adjacent electrode 32, 46 must be permeable to the third ions 94 andthe fourth ions 96. More specifically, a sufficient number of the thirdions 94 and the fourth ions 96 must be able to penetrate within theadjacent electrode 32, 46 in response to the application of the secondvoltage V₂, to cause a sufficient change in the electrochemicalpotential of the adjacent electrode 32, 46 that enables the secondarybattery 22 to store the predetermined amount of electrical energy. Acathode layer 46 that contains a host lattice 54 having a conjugatedsystem with delocalized π electrons may be used as the adjacentelectrode 32, 46. Alternatively, an anode layer 32 may be used as theadjacent electrode 32, 46. Such an anode layer 32 may be formed, forexample, as an open-cell foam or a solid of particles or granules boundtogether.

Because of the electrical isolation between the remote electrode 32, 46and the fast charge composite 60, the second voltage V₂ can be differentthan the first voltage V₁. This means that it is possible to apply asecond voltage V₂ that is in excess of the maximum voltage V_(MAX),which would cause damage to the first electrolyte 44 and/or the membrane38 and/or either of the electrodes 32, 46 if it were to be appliedbetween the electrodes 32, 46.

In one embodiment, the adjacent electrode 32, 46 is the cathode layer46, and the remote electrode 32, 46 is the anode layer 32, and each ofwhich is electrically isolated from the fast charge layer 30.

In a second, alternative embodiment, the adjacent electrode 32, 46 isthe anode layer 32 and the remote electrode 32, 46 is the cathode layer46, and each of which is electrically isolated from the fast chargelayer 30.

The present invention also provides a method for constructing a fastcharge composite 60 combined with a secondary battery 22.

The method includes the steps of: stacking a separator 62 ofelectrically insulating material upon and parallel to either the anodelayer 32 or the cathode layer 46 rendering it the adjacent electrode 32,46, stacking a fast charge layer 30 of thermally expanded graphite foil66 upon and parallel to the separator 62 so the separator 62 is disposedbetween the and the fast charge layer 30, and attaching a fast chargelead 68 in electrical contact with the fast charge layer 30 with aconductive adhesive 52 of graphite paint.

The method includes steps for producing a second electrolyte 64,including: dissolving AlCl₃ powder in ethanol to saturation to create abackground solution 78, combining 40 wt % of the background solutionwith 60 wt % of glycerol to make a binary solvent, grating 1 cm³ of 99.4to 99.9 wt % of Aluminum of 99.95% purity and 0.1 to 0.6 wt % of Indiumto make filings with an equivalent surface area of 20 to 30 cm²,immersing the filings in 150 to 200 ml of the binary solvent until thefilings have dissolved to produce a second electrolyte 64 that includesthird ions 94 that contain Aluminum and have a positive charge andfourth ions 96 that contain Aluminum and have a negative charge.

The method concludes with the step of wetting the separator 62 with thesecond electrolyte 64.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings and may be practicedotherwise than as specifically described while within the scope of theappended claims. That which is prior art in the claims precedes thenovelty set forth in the “characterized by” clause. The novelty is meantto be particularly and distinctly recited in the “characterized by”clause whereas the antecedent recitations merely set forth the old andwell-known combination in which the invention resides. These antecedentrecitations should be interpreted to cover any combination in which theinventive novelty exercises its utility. The use of the word “said” inthe apparatus claims refers to an antecedent that is a positiverecitation meant to be included in the coverage of the claims whereasthe word “the” precedes a word not meant to be included in the coverageof the claims. In addition, the reference numerals in the claims aremerely for convenience and are not to be read in any way as limiting.

ELEMENT LIST Element Symbol Element Name 20 fast charge system 22secondary battery 24 first ions 26 second ions 28 electroactive layer 30fast charge layer 32 anode layer 34 negative battery lead 36 cement 38membrane 40 third thickness 42 pores 44 first electrolyte 46 cathodelayer 48 carrier sheet 50 positive battery lead 52 adhesive 54 hostlattice 56 voids 58 dopant 60 fast charge composite 62 separator 64second electrolyte 66 foil 68 fast charge lead 78 background solution 80binary solvent 82 filings 92 particles 94 third ions 96 fourth ions I₁first current I₂ second current I_(MAX) maximum current P_(FC) secondelectrical power P_(MAX) maximum charging power T₁ first time intervalT₂ second time interval V₁ first voltage V₂ second voltage V_(MAX)maximum voltage

What is claimed is:
 1. A method for constructing a fast charge composite(60) combined with secondary battery (22) having an anode layer (32) anda cathode layer (46), said method comprising; stacking a separator (62)of electrically insulating material upon and parallel to one of saidanode layer (32) and said cathode layer (46) rendering it an adjacentelectrode (32, 46), stacking a fast charge layer (30) upon and parallelto the separator (62) with the separator (62) disposed between saidadjacent electrode (32, 46) and said fast charge layer (30), andcharacterized by, dissolving AlCl₃ in ethanol to create a backgroundsolution, combining the background solution with glycerol to produce asecond electrolyte (64) including third ions (94) having a positivecharge and including fourth ions (96) having a negative charge, wettingthe separator (62) with the second electrolyte (64).
 2. A method forconstructing a fast charge composite (60) combined with a secondarybattery (22) having an anode layer (32) and a cathode layer (46), saidmethod comprising; stacking a separator (62) of electrically insulatingmaterial upon and parallel to one of said anode layer (32) and saidcathode layer (46) rendering it an adjacent electrode (32, 46), stackinga fast charge layer (30) of thermally expanded graphite upon andparallel to the separator (62) with the separator (62) disposed betweenthe adjacent electrode (32, 46) and the fast charge layer (30),attaching a fast charge lead (68) in electrical contact with the fastcharge layer (30) with an adhesive (52) of graphite paint, andcharacterized by, dissolving AlCl₃ powder in ethanol to saturation tocreate a background solution, combining 40 wt % of the backgroundsolution with 60 wt % of glycerol to make a binary solvent, grating 1cm³ of 99.4 wt% to 99.9 wt % of Aluminum of 99.95% purity and 0.1 wt% to0.6 wt % of Indium to make filings with an equivalent surface area of 20cm² to 30 cm², immersing the filings in 150 ml to 200 ml of the binarysolvent until the filings have dissolved to produce a second electrolyte(64) including third ions (94) containing Aluminum and having a positivecharge and including fourth ions (96) containing Aluminum and having anegative charge, wetting the separator (62) with the second electrolyte(64).